1. Field of the Invention
The present invention relates to a plug socket with a high-current contact for establishing a high-current electrical connection, comprising a metal body formed along a portion of its longitudinal extent as a hollow cylinder section and a contact spring jack received in the hollow cylinder section and having a plurality of linear, substantially hyperbolically extending, contact elements connected at their opposite ends by respective circumferential material bands, with the contact spring jack being secured, at one of its opposite ends, in the metal body without a possibility of axial displacement.
2. Description of the Prior Art
A plug socket with a high-current contact is disclosed in patent No. 67,484 of the former German Democratic Republic. In the structure disclosed in this patent, a metal body in which a form-stable contact spring jack is received, is formed of two parts. The metal body consists of a so-called solder connector bolt and a sleeve encompassing the contact spring jack. The metal body is formed as a unitary element by pressing into the sleeve stays for the soldered connector bolt, with the contact spring jack being pressed in with its inner end metal band between the connector bolt stays and the jack encompassing sleeve. This construction is based on an assumption that the main load, upon establishing of the plug-in connection, acts in the direction of the plug socket bottom and, therefore, a support of the contact spring jack against a radially protruding collar of the solder connector bolt is sufficient to take up the main load, which is generated upon establishing of a releasable plug-in connection, and is applied to the plug socket. To insure a sufficient reliability of the press connection between the solder connector bolt and the contact spring jack and the jack-encompassing sleeve and for purposes of economical manufacturing of the plug socket, it was deemed sufficient to provide knurling in stays for the soldered connector bolt which engage the contact spring jack or the jack-encompassing sleeve.
However, the question remains whether in view of unavoidable tolerances and, in particular, tolerance pairing, necessary in mass production, the foregoing assumption for a plug socket with high-current contact of this type is valid or not. This is because the multi-part construction requires noticeable production expenses for both manufacturing and the assembly with a following alignment and pressing of the three separate parts of the plug socket.
In order to eliminate or to reduce the drawbacks associated with this type of plug sockets and connected with the relatively high production expenses or with mechanical rigidity, German patent No. 3,528,587 proposes to provide the stays of the soldered connector bolt, which engage the jack-receiving sleeve, upon assembly of the plug socket, with a radial constriction. Thereby, upon connection of the soldered connector bolt with the sleeve, a formlocking support is formed between the soldered connector bolt and the jack-receiving sleeve in the plug-in direction, preventing the displacement of the jack in the plug-in direction. This formlocking support insures the integrity of the plug socket when the jack-receiving sleeve, together with the jack, is pressed against the stays constriction and is supported thereagainst.
Though the radial constriction permits to achieve a reliable formlocking, tolerance-insensitive support in an axial direction, at least within certain limits, of the separate elements of the plug socket, other drawbacks such as, e.g., as high production costs, which are connected with a need to produce a multi-part socket, remain.
In another type of plug sockets with high-current contact for establishing an electrical plug-in connection, the jack encompassing sleeve and the soldered connector bolt are formed as a one-piece part. However, in these plug sockets, such as shown and described in European publication EP-0 653 808, the free front end of the spring jack is connected with the jack-receiving sleeve by a press fit and, possibly, other formlocking means. The rear end of the contact spring jack is axially and radially spaced with respect to the jack-receiving sleeve or from a surface defining a hollow space provided in a metal body. The plug socket shown in this European Publication has a simplified construction and fewer parts, which simplifies its assembly. However, with this construction, the advantage of a formlocking support for the contact spring jack in the plug-in direction is given up.
Accordingly, an object of the present invention is to provide a plug socket with a high-current contact which can be cost-effectively produced.
Another object of the present invention is to provide a mechanically rigid, in opposite plug-in directions, plug socket formed of only two parts.
A further object of the present invention is to provide a plug socket the operational characteristics of which are independent form manufacturing tolerances to a most possible extent.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a plug socket with the contact spring jack anchored, at its rear, with respect to a plug-in direction, end in the hollow cylinder section with a press fit, and with its front, in the plug-in direction, end forming a sliding fit connection with the hollow cylinder section.
With this construction, together with the smallest possible manufacturing expenses for all parts and completely independent of the quality of the press fit between the contact spring jack and the inner wall of the hollow cylinder-defining bore, an absolutely reliable formlocking support of the contact spring jack in the plug-in direction of the associated connection pin in the metal body achieved. This advantage is insured, completely independent of tolerances, when the contact spring jack is defined as a rolled-up sleeve formed of a sheet metal strip and with contact strips defined by punched-out sections. Such a sleeve substantially reduced total costs of production of a plug socket with high-current contact. An additional advantage of the structure according to the present invention consists in that in case when necessary or desirable, the contact spring jack can be secured against displacement in the pull-out direction of the associated contact pin in a simple manner during an operational step in which the contact spring jack is inserted in the hollow cylinder section of the metal body.
According to an advantageous embodiment of the present invention, the hollow cylinder section of the metal body has, at its inner end, a radially widened inner diameter portion. This enables, in the same operation step, i.e., without additional expenses, simultaneously with formation of the press fit between the rear or inner band of the contact spring jack and the inner wall of the hollow cylinder portion, to form of formlocking connection of the two parts, the contact spring jack and the metal body, with respect to the pull-out direction of the contact pin which cooperates with the plug socket. It is particularly advantageous when the depth of the radially widened inner diameter portion corresponds at least to a portion of the thickness of the material band connecting the contact wires or contact strips of the contact spring jack with each other.
In connection with the securing one end of the contact spring jack without a possibility of axial displacement at the bottom of the hollow cylinder of the metal body, the end of the contact spring jack adjacent to the free end of the hollow cylinder forms a sliding fit therewith. Thereby, a length equalization between contact strips of the contact spring jack movable outwardly upon insertion of the contact pin into the jack, is insured. In accordance with a particularly preferred embodiment of the present invention, which insures an exact guidance of the free end of the contact spring jack, the hollow cylinder section of the metal body has, at its outer free end, a radially widened inner diameter portion formed as a cylindrical portion over a major portion of an axial extent of the associated metal band of the contact spring jack. Preferably, the depth of the inner diameter portion is relatively small so that the circumferential material band, which forms the free end of the contact spring jack contacts the inner circumference of the cylinder without any noticeable pressure and forms therewith only sliding fit.
In order to additionally secure the contact spring jack in the direction of which the contact pin is pulled-out, the hollow cylinder section has, in a region of its outer end, at least at one location of its circumference a directed radially inward, reduce inner diameter portion.
According to a simplified embodiment of the present invention, the reduced inner diameter portion can be formed as a bead engaging an outer end surface of the metal strip which is provided at the free end of the contact spring jack.
However, within the scope of the present invention, means for an additional securing of the contact spring jack in the axial direction is not limited to the bead, and the reduced inner diameter portion can be formed as a directed radially inward projection.
In accordance with still further embodiment of the present invention, the metal body can have, at its end, opposite the hollow cylinder section, a section for connection with a stranded cord or conductor, which is formed integrally with the hollow cylinder section. At that, the metal body can be formed as a one-piece rotatable member having a reduced diameter section connecting the hollow cylinder section with the connection section.
However, the plug socket according to the present invention is not limited to the above-discussed embodiments and can be formed, e.g., of a radially deformable metal pipe section or of a similar semi-finished morkpiece.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to it construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.